1. Field of the Invention
The present invention relates to a production management system, and more particularly, to a production management system for carrying out efficient physical circulation and multi-product variable production management on a semiconductor manufacture and development line.
2. Background Art
Various production management systems concerning manufacture of a semiconductor have hitherto been put forward.
For instance, Japanese Patent Application Laid-Open No. 2648/1996 describes a simulator for predictively controlling the volume of material to be physically distributed and having the function of checking the real situation against the result of simulation, as well as a re-simulation function. Japanese Patent Application Laid-Open Nos. 192906/1996 and 296067/1995 describe a method for predicting and optimizing the amount of material to be physically distributed, by means of applying the result of simulation of physical circulation online. Japanese Patent Application Laid-Open Nos. 76813/1996, 41114/1995, and 314107/1994 describe simulation (or modeling) techniques based on a network model. Japanese Patent Application Laid-Open No. 50466/1997 describes a method for simulating routes for physical circulation. Japanese Patent Application Laid-Open No. 17837/1997 describes a method for optimizing batch processing and improving the efficiency of processing, such as prediction of identical processing, by combination of a track record computer and a physical-circulation simulator. Japanese Patent Application Laid-Open No. 55393/1998 describes a method of improving efficiency of processing, such as prediction of identical processing, for preventing set-up and replacement of facilities on a multi-product production line, by means of optimizing batch processing through a lot integration simulation based on process information. Further, there is proposed a method for performing a simulation through use of parameters, such as material stock information and a shipment schedule.
FIG. 6 is a chart showing an example of a conventional production management system.
In the drawing, LAN designates a local area network illustrated by a single wire; reference numeral 1 designates a production line having a plurality of pieces of production apparatus (Apparatus #A, Apparatus #B, . . . Apparatus #XX); and 2 designates a production controller connected online to the production line 1 by way of the LAN. A designation parameter a dispatch rule, a simulation period, or the like) and an automatically-extracted parameter (a processing time, of single wafer processing and batch processing, for each recipe, or an equipment path for each device or process) are assigned to the production controller 2. The production controller 2 manages data pertaining to all manufacturing apparatus disposed in and all production lots to be produced on a production line.
Reference numeral 3 designates a simulator and database and is connected to the LAN. The simulator 3 accesses the production controller 2 and extracts from the same track record data such as processing times or previously-prepared data. Through use of the thus-extracted data, the simulator 3 performs simulation or re-simulation. Reference numerals 5A to 5E designate office terminals connected to the LAN. The terminals 5A to 5E control handling of data and the operation of the simulator 3.
The pieces of manufacturing apparatus #A, #B, . . . #XX disposed on the production line 1 are responsible for respective steps of the process for manufacturing, for example, a semiconductor device. In the drawing, predetermined material is supplied to the apparatus #B as a lot. After having been processed by the apparatus #B, the material is returned to the apparatus #A, as indicated by an arrow. The material is then processed by the apparatus #A. Similarly, the material is supplied to apparatus #C, #D, and #XX. In each apparatus, the material is processed.
An arrow extending from the apparatus #XX to the apparatus #A indicates a case where, after having been processed by the apparatus #XX, material is sent to the process of apparatus #A, where the material is processed again. In connection with such a production line 1, the production controller 2 performs forward scheduling or backward scheduling of events according to a desired physical distribution rule (a dispatch rule) through use of track record data or previously-prepared data, such as a processing time, in real time or off line, in consideration of a factor responsible for deteriorating the efficiency of batch processing or set-up/replacement operation. The production controller 2 controls and causes the simulator 3 to perform simulation or re-simulation, thus predicting the volume of material to be physically distributed.
The conventional production management system has the foregoing configuration and is suitable for use with a line on which is delivered a lot for which processing time and flow have been predetermined; that is, a single-product mass production line. However, the production management system cannot cope with physical distribution parameters which vary with time, on a variable multi-product production line; particularly, a line for simultaneously effecting manufacture and development of a product. For this reason, the conventional production management system is not suitable for use with a development lot for which a process flow has not been determined or with a development line in which there frequently arises a change in the process flow of an introduced lot, addition of a process flow, or an interruption by a process requiring an unknown amount of time to perform processing such as a reproduction, testing, or inspection operation.
Customization of a commercially-available general-purpose simulator involves consumption of much time, and in many cases a customized simulator is not applicable.
The present invention has been conceived to solve the foregoing drawbacks of the conventional method and system. The present invention is aimed at achieving an optimal result of physical distribution by means of dynamically changing a dispatch rule (a physical distribution rule) in a case where a failure is predicted to arise, in consideration of a time-series predicted value pertaining to an in-process load as well as a predicted value pertaining to the volume of material to be physically distributed (i.e., a load factor of a processing apparatus).
The present invention is also aimed at eliminating a problem of a conventional simulator failing to exhibit an optimal solution, by means of improving the accuracy of simulation through the steps of: capturing all data pertaining to a disturbance factor such as a scheduled time for starting and terminating an inspection, a scheduled time for starting and terminating a test, and a scheduled time for starting and terminating maintenance of a production apparatus; and immediately replacing data with new data and performing re-simulation in a case where the data are modified.
The present invention is aimed at providing a production management system which performs at least one simulation operation and utilizes, for improving the accuracy of a simulation operation, the following items as parameters of a re-simulation operation while using data pertaining to the simulation result as initial data; namely,
(1) a load factor of a processing apparatus and time-series test data pertaining to an in-process load factor;
(2) disturbance factors, such as a test, an inspection, reproduction, a change in process flow, introduction of a new lot, or maintenance of a processing apparatus; and
(3) a dynamic change in a dispatch rule, thereby implementing an optimal set-up function including scheduling of dynamic physical distribution.
According to one aspect of the present invention, a production management system comprises a production controller connected online to a plurality of pieces of production apparatus, or a data processing apparatus connected online to an off line management apparatus having a production management function and a simulator.
The simulator performs a simulation of physical distribution for a specified period of time through use of a simulation parameter, apparatus information, and process information, which are acquired from the production controller or the offline management apparatus. The simulator further performs a re-simulation of physical distribution while taking, as parameters for optimizing physical distribution, time-series data pertaining to the availability factor of each apparatus and the load factor of each apparatus obtained as a result of the previous simulation, as well as the start and termination times of an event which is to arise in the period of a simulation. Then, the production controller dynamically changes a dispatch rule set for each apparatus or a group of pieces of apparatus having a same function, thus feeds back the change to control of real physical distribution.
In another aspect of the present invention, in the production management system, the re-simulation of physical distribution is performed automatically or at a predetermined timing while occurrence of an event is used as a trigger, and the result of the simulation is retained in the simulator or an external computer connected thereto and can be transmitted.
In another aspect of the present invention, in the production management system, reporting of occurrence of the event is registered or changed while start and termination times or scheduled start and termination times output from a portable terminal, the production controller or the offline management apparatus, or the simulator are taken as parameters. The registered report is registered in the simulator or an external computer connected thereto. A re-simulation of physical distribution is performed automatically or at a predetermined timing after completion of registration of the report, and the result of the re-simulation is immediately transmitted from the simulator or from the external computer connected thereto.
Other features and advantages of the invention will be apparent from the following description taken in connection with the accompanying drawings.